Creating a bug balance is definitely the MOST EFFECTIVE way to control insect pressure on your garden crops.
I put in Beetle Banks and other insectary strips through out my garden field, both as perennial and no till rows down the middle and as part of the border around the garden.
One of the best books on how to nurture good bugs and establish a positive ratio of good insects on your property is Farming with Native Beneficial Insects published by the Xerces Society. Xerces is a great organization dedicated to preserving invertebrates.
What is a Beetle Bank?
Beetle Banks are quite popular in Great Britain but are not nearly as well known here in the U.S. But the concept is basically the same thing to an insectary strip or perennial no-till row - Beetle Banks are another type of garden or field space reserved for beneficial insects - it is left undisturbed or uncultivated - so beneficial insects can seek a haven there and safely live, hibernate, and breed.
How to Build a Beetle Bank
Beetles will be more attracted to wider rows and larger areas. Make your beetle bank row at least 2 feet wide.
Mound up the soil about 6 inches or so, then plant the grasses or other natives in the mound. These grasses will form nice, large clumps - plant them about 1 - 1.5 feet apart.
For the first year or two, you will need to give your Beetle Bank and the native grasses a bit of attention. Keep it weeded so grasses can get themselves established without any weed pressure. You can also trim your grasses to promote a fuller clump.
After the second year though, the grasses can take care of themselves, and you will find that only a little spot weeding will be necessary.
Predatory Ground Beetles
Predatory ground beetles are great controls for aphids and many other garden pests. They have voracious appetites like their cousins, the Ladybugs. You have almost definitely seen them as you dig holes for planting - these are the large shiny black beetles that scurry away as you dig. Some have textured ribbing on their wing covers and some also have a green or purple sheen. Sometimes they have formidable looking pinchers!
The thing that makes ground beetles more useful to gardeners than Ladybugs is that they hang around. They don't fly away when the food supply get low. Ladybugs are very effective in enclosed areas like a greenhouse or for spot treatment of aphid infestations. But Ladybugs get nervous as soon as the aphid population starts to decrease and off they fly, leaving behind a couple aphids who start breeding again immediately.
We will also have some of these native grasses in pots inoculated with Eyebright and Betony (Pedicularis canadensis) for $12 each at our 2019 Plant Sales!
Panicum virgatum "Rotstrahlbusch" - Switch Grass
A beautifully colored variety of native Switch Grass. This one has an upright and arching habit, and acquires striking dark reddish burgundy coloring as the weather cools in fall. The cooler the weather, the darker the red coloring. In warmer winters, the color retains greenness.
Switch Grass is hardy, easy, and maintenance free - just keep it weeded the first season or two until it forms a weed-resistant clump. Trimming it in the first year helps promote bushiness.
Like all of the native grasses we sell, this is a clumping grass and will not spread or become invasive.
Switch Grass is not picky about soil, but need good drainage. Full sun is best. This clump of grass can provide ground beetles and other beneficial insects with a haven in your garden.
Can get as high as 4 feet.
Sold in mid-April @ $4.75 per 4" pot
Schizachyrium scoparium - Little Bluestem Grass
Little bluestem is a native prairie grass, one of the main components that make up the prairie biome. It is a great clumping style grass, very appropriate for growing almost anywhere in the country.
Little Bluestem is a shorter grass, about 4 feet high. It has a fine texture, with thinner blades growing in mass creating a bushy appearance. It has a beautiful blue-green coloring during the growing season.
Like all the grasses we are introducing to our plant collection in 2016, Little Bluestem is hardy and easy to grow. Any soil type is doable as long as there is plenty of sunlight. Little Bluestem is a great grass species for any managed meadow project. Once clumps are established, there will be little need for weeding or maintenance. This grass will not become invasive in any way.
A grouping or bank of these clumping grasses will provide a safe haven to ground beetles and other beneficial insects like lacewings.
Sold in mid-April @ $4.75 per 4" pot
I chose these three native varieties out of a huge list of native grasses, as I felt that they would compliment one another beautifully if grown in a cluster together.
They all share similar growing conditions and are all easy to grow and maintain.
I liked the texturing of the thick Big Bluestem combined with finer, bushier, Little Bluestem. I also really liked how the greener and then reddish Switch Grass will set off the bluish and purplish coloring of the Blustems. These grasses each could, of course, also be grown a single species, and each would work fine as a beetle bank or insect-attracting grass on their own.
We're planning to have these ready for you to plant as the soil warms up in May.
Ground beetles like to establish themselves in a particular location and stay put there. So that's why a Beetle Bank works so well for them. The Bank gives them an undisturbed area where they can retreat while cultivation is occurring or for the winter. And because the Beetle Bank is in your garden or surrounding your garden, the beetles are close by your plants when it is time to search for food.
Beetle Banks attract all sorts of great beetles - if you're a beetle fan, you will be happy to know that fancy rare Stag Beetles and others will see your Beetle banks as a haven!
Also, don't fret about a Beetle Bank being a haven for the non-beneficial, "wrong kind" of beetles. These banks are designed to appeal to carnivorous beetle types. Beyond that, the best way to keep your bad bug populations at bay is to bring in more good bugs. You should always be trying to establish a balanced ratio between the good and the bad bugs.
Beetle Banks are a new twist on the very traditional Hedgerow. It seems that people thought hedgerows looked messy and unruly, and so they were replaced with fences. But the hedgerow was able to harbor and protect a huge array of beneficial bugs that a fence can never live up to!
Beetle Bank Planting Choices
Native clumping grasses are wonderful plants for using in creating Beetle Banks or any insectary planting. The clumps make well-protected houses, and the clumping habit keeps the grasses under control in your garden. When I am choosing plants for a Beetle Bank, I like a variety of color and texture in the grass and I can't help but include some native flowering plants as well like Mountain Mint or Monarda that just bring in and attract all sorts of other beneficial insects. Ground Beetles are not just carnivores - they like nectar too and many species have been known to eat weed seeds as well.
You'll probably also find Lacewings seeking out your Grassy Beetle Bank, as they also like to establish a home base. Lacewings are fabulous predators and are huge consumers of aphids
Andropogon gerardii - Big Bluestem Grass
This is the native variety of Big Bluestem - a great big earth-saving wonderful grass, reaching up to 8 feet high.
Big Bluestem forms a thick clump and will not spread or become invasive. But after you do a bit of minimal care in the first season or two, it will be a dependable entity in the garden, attracting and providing shelter for beneficial insects. Big Bluestem is perfectly hardy and maintenance free.
This is also a very attractive grass with thick blue-green blades. The lower stems have a striking purple-blue color. The individual blades of this grass are wide and create a substantial and abundant look to the clump.
Because this is a very tall grass, plan it for back edges where it won't shade other plants. Where ever you plant it, Big Bluestem will provide a wonderful shelter for beneficial insects like ground beetles and lacewings. The more clumps of Big Blue Stem you have, the easier it will be for beneficial insects to find and more beneficials your insectary strip or beetle bank will be able to support.
This native grass is not picky about soil conditions, although it grows best in full sun with good-draining soil.
Big Bluestem is one of the starts of the native, tall-grass prairie biome.
Sold in mid-April @ $4.75 per 4" pot